Multiple Access Interference (MAI) is a significant source of interference (noise) that limits the capacity and performance of Code Division Multiple Access (CDMA) wireless services. Higher data rate services like those provided by Wideband CDMA (WCDMA) systems exacerbate this situation as processing gain is reduced and must be compensated for by higher power (signal) levels, which in turn limits capacity for those applications.
A number of techniques have been conceived for mitigating MAI in spread spectrum wireless systems and thus improving overall network performance. The proposed solutions may be grouped into at least three classes: adaptive antenna array technology, multi-user receivers, and rapid power control. One class of these techniques employs adaptive array techniques along with specialized adaptive processing to improve network performance. U.S. Pat. Nos. 6,154,485; 6,141,567; 6,115,409; 6,108,565; 6,100,843; 6,061,553; 6,031,877; 5,930,243; 5,904,470; and 5,828,658 are examples of these techniques.
Another class of techniques utilizes complex algorithms in the receiver to concurrently estimate the signals from multiple users utilizing a technique referred to as MUD or variants thereof. U.S. Pat. Nos. 6,137,843; 6,108,564; 6,081,516; 6,014,373; 6,002,727; 5,956,333; and 5,719,852 are examples of these technological schemes.
A third class of techniques involves network link performance monitoring and control functions including monitoring and controlling transmitted powers from the base station and the mobile station and/or monitoring and controlling link signal quality metrics to mitigate MAI and improve overall network performance. Examples of this technology include U.S. Pat. Nos. 6,167,031; 6,131,049; 6,157,619; 6,119,010; 6,118,983; 6,104,933; and 6,088,335.
While the above-referenced patents disclose ways to improve WCDMA network performance within the specific technology (adaptive antennas and adaptive processing, MUD filtering techniques, or network quality performance monitoring and enhancement), they do not address those technological opportunities that collectively improve system performance across the entire receiver architecture.
Some aspects of this invention which separate it from other published and patented systems and methods are an integrated receiver architecture configured with a suite of signal processing algorithms incorporating the power of both STAP and MUD and the real-time control algorithms that assigns/allocates processing requirements. This architecture seeks, among other things, to optimize WCDMA network performance against practical real-time system constraints, notably computational complexity (cost) and network performance (throughput), and latency.